Noise pollution turns up volume in national parks
Even official wilderness areas are not safe from manmade racket
America’s natural places, supposedly the last bastions of peace and quiet, are contaminated by the sound of honking cars, roaring jet engines and other noise, scientists found.
Sixty-three percent of protected areas in the continental United States suffer from significant human-caused noise, according to a study in this week’s Science. The protected areas spanned national forests sprawling over millions of acres to local parks.
Such areas are “where people go for respite from the hustle and bustle of modern life,” says study co-author Rachel Buxton of Colorado State University. “Unfortunately, we found that a good percentage of them experience levels of noise pollution.”
In more than 60% of the nation’s parks and other protected areas, artificial noise is so intrusive in some spots that a sound that would be audible at a distance of 100 feet can be heard only at half that distance. In 21% of protected areas, there are spots where a sound normally heard from 100 feet away can be heard only from a distance of 10 feet.
The loudest areas had “shockingly high levels that can potentially be bad for human health,” says study co-author George Wittemyer, also of Colorado State University.
The biggest culprits: vehicles such as cars and trucks; aircraft; and the din of natural resourcebased industries such as oil and gas extraction.
The researchers measured sound levels at nearly 500 sites in various protected areas. Then they combined the sound data and other information, such as elevation and distance from roads, to create a formula that predicts both human noise and natural sound levels. They applied their formula to thousands of protected areas, from neighborhood parks to huge wildlife refuges.
The results showed noise pollution “is pervasive,” the study’s authors write. Even 12% of official wilderness areas, where motorized equipment and vehicles are almost entirely banned, suffered significant noise pollution.
That wildernesses and other “last strongholds of wildlife are exposed to substantial (humanassociated) noise, a known pollutant, is troubling,” says Boise State University’s Jesse Barber, who was not part of the study.
In the majority of protected areas, enough noise infiltrates the quiet to annoy visitors. Noise pollution also can affect bird song, predators’ ability to find prey, and prey’s ability to hear predators.
The findings provide a nationwide look at the problem, says Nicholas Miller, the recently retired founder of a noise- and vibration-control consulting firm who was not one of the authors. The study “is a warning,” he says, at a time when sound levels are increasing.
The good news is the researchers found that the tapestry of natural sounds is still intact in many places, most of them national parks and large wilderness areas.
“We still have some incredibly natural soundscapes across the United States,” Wittemyer says. “If we want to keep them, we want to think about it.”
The culprits: cars and trucks; aircraft; and the din of natural resourcebased industries such as oil and gas extraction.